staging: wilc1000: replace numerical constant with predefined MACRO

Replace the pre-defined macro signifying the ethernet protocol type
defined in the kernel headers instead of the numerical constant

Signed-off-by: Hari Prasath Gujulan Elango <hgujulan@visteon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>